Step 6: Applying heat to Shrink Sleeve

To power a DIY LED lab project for a group of inexperienced students, I was looking for an inexpensive, clean, and visually attractive solution to attach a Coin / Button battery to a LED circuit.

After trial and error, I found the following method of heat shrinking wire leads onto the Coin / Button battery terminals to be relatively easy and low cost along with conserving space, providing battery short protection, and was visually attractive.

For lack of a better name, I refer to it as a “Heat Shrink Coin & Button Battery Holder”.

Disclaimer: This “Instructable” is provided “As Is” without any express or implied warranty of any kind including warranties of merchantability, noninfringement, or fitness for a particular purpose. The Author of this “Instructable” does not warrant or assume responsibility for the accuracy or completeness of any information, text, graphics, links or other items contained within this “Instructable” post. In no event shall the Author of this “Instructable” be liable for any damages whatsoever (including, without limitation, lost profits, business interruption, lost information, or damaged electronic equipment and circuits) or be liable for any personal harm / pleasure / death whatsoever (including intentional or unintentional, without limitation, cuts, scratch, punctures, bruises, inhalation, swallowing, or insertions) arising out of the use of or inability to use this “Instructable”, even if the Author of this “Instructable” has been advised of the possibility of such damages or personal risks.

In short... Do your own engineering work and analysis of the approach for your specific implementation to determine validity, safety, and assume accountability for the outcome of your engineering assessment; assess and mitigate the risks specific to your scenario and skill level. Use good sense on how, where, and if to use this approach; if you are unsure, do not use it... I would have said common sense, but common sense is definitely not common.

I did attempt other approaches to secure a Coin / Button battery to a LED circuit; however, my results were mixed.

Incorporation of a button battery holder: Due to confined space and the significant cost adder per project kit, I decided that a molded battery holder was not a viable option.

Variety of taping methods (including some illustrated here on instructables): Taping was not giving me the clean look I desired. Nor was the taping method necessarily easy when attempting to position and secure two loose wire leads to the Coin / Button battery terminals as you wrapped tape around it by yourself.

Solder directly onto the battery terminals: Soldering to the battery yielded limited success and I was concerned with my student’s ability to utilize this method along with any potential battery damage due to excessive heat. I did evaluate batteries with soldering tabs; however, I found them to be a significant cost adder compared to a regular bulk Coin / Button battery.

Conductive glue / epoxy: Yielded similar frustrations as taping and came with the additional concerns around the chemical makeup.

Price: Depends on supplier and volume. If you are buying in large volumes, I recommend hunting around for the best deal.

Item: 22-Gauge Solid Hookup Wire

Use: Used to make battery leads which provide continuity from battery to the desired circuit. I prefer using two colors (Red and Black) to label polarity when attached to the battery; however, use whatever color you want.

Price: 22-Gauge Solid Hookup Wire is pretty inexpensive. On average it costs less than 1 cent per inch. At your typically electronic store, you can pick a 25’ spool for about $3.00.

Item: Polyolefin Heat Shrinkable Tubing

Use: Provides a compression / mechanical bond of the two individual 22 Gauge Wire Leads to the Coin / Button battery terminal once shrunk when heat is applied. Each Coin / Button battery usually requires a different Heat Shrinkable Tubing diameter size.
In my trials, I have found that the following batteries work well with the following 1-2 Heat Shrink Tubing diameters and sleeve lengths:

Price: Price really depends on volume and from where you purchase. For example, allelectronics.com has 1/2" X 4' Heat Shrink Tube in black for about $2.50. So if you were using that tubing for the CR2032 batteries, which needs a length of about 1 1/4 inches for the sleeve, you would get about 38 sleeves out of those 4 feet at an average cost of 6 cents a sleeve.

Step 2: Preparing the Wire Leads

Grab the 22-Gauge Solid Hookup Wire and cut two segments to the desired length for your project. For ease of identification, I choose Red wire to represent my positive lead and Black wire to represent my negative lead; each will be connected to their respective positive and negative battery terminals. For both wires, strip the insulation roughly the length of the Coin / Button battery diameter you are using for your project.

Once the insulation has been stripped, twist the bare wire around the needle nose pillars in a circle so that it starts to take a spiraling shape. The spiraling shape of these wire end bends will maximize the surface area between the wire lead and the battery terminal while providing compression tension to hold the wire leads in place between the battery terminal and Heat Shrink Sleeve.

Step 3: Preparing the Heat Shrink Sleeve

I have found that 1-2 Heat Shrinkable Tubing (which shrinks to 50% of its original diameter when heated) works well for this scenario. As a general "rule of thumb" when selecting a Heat Shrink Tubing diameter for this project, select a diameter that is 65% the diameter of the battery you are using if the battery height is less than 3.5mm; if the battery height is greater than 3.5mm, select a Heat Shrink Tubing diameter equal to the Coin / Button battery diameter. Note that Heat Shrinkable Tubing is usually labeled and sold in pre-shrink diameters.

The length of the Heat Shrink Sleeve, or a cut segment of the Heat Shrink Tubing, will also vary based on the battery diameter. Typically a sleeve length of 1.5 times the battery diameter works pretty well to encapsulate the battery and wire leads. Since the Heat Shrink Tubing is sold in long strips, it will likely be necessary to cut it with a pair of scissors or utility knife to the optimal length.

In my trials, I have found that the following batteries work well with the following 1-2 Heat Shrink Tubing diameters and sleeve lengths:

Step 4: Inserting the Coin / Button battery into Heat Shrink Sleeve

Once you select the right Heat Shrink Tubing diameter and cut it to the desired sleeve length, it may be necessary to stretch the internal diameter of Heat Shrink Sleeve slightly to allow the battery to fit.

First test fit the battery to see if you can get the Coin / Button battery into the Heat Shrink Sleeve without stretching it. If stretching is required, I found inserting needle nose pillars into the Heat Shrink Sleeve and prying the handles outward gently to be an effective method of increasing the internal diameter of the Heat Shrink Sleeve. Be careful not to over stretch the Heat Shrink Sleeve during this process; a little effort goes a long way, so just stretch it a little at a time until you can get the Coin / Button battery in with a snug fit.

When you insert the Coin / Button battery into the Heat Shrink Sleeve, position the battery slightly off centered between the open ends of the Heat Shrink Sleeve. Because of the snug fit, it may be necessary to nudge the battery through the sleeve. Pushing with the needle nose pillars, in the closed position, seems to be an effective method of advancing the battery within the sleeve.

When you are inserting the Coin / Button battery into the Heat Shrink Sleeve, it will be beneficial to note which battery sides are the positive and negative terminals. It will be difficult to tell which is which once the battery is inserted in the Heat Shrink Sleeve.

Step 5: Inserting Wire Leads into Heat Shrink Sleeve

With the battery positioned in the Heat Shrink Sleeve, we are now able to insert the previously prepared wire leads onto the Coin / Button battery terminals. When inserting the wire lead between the Coin / Button battery terminal and Heat Shrink Sleeve inner skin, ensure you have the spiraling wire end pointing towards the battery terminal; this will reduce the risk of the wire ends from puncturing through the Heat Shrink Sleeve along with providing a slight spring tension when compressed. If you positioned the battery slightly off centered in the Heat Shrink Sleeve, insert the wire leads from the side of the sleeve with the longer length; when the sleeve is shrunk, this will allow more sleeve to be wrapped around the wire leads.

Also make sure that you push the wire lead through enough so that the insulation of the wire is leaning on the Coin / Button battery terminal; this will reduce the risk of the wire lead shorting the two Coin / Button battery terminals. If you had specific wire colors designated for each battery terminal polarity, this is the time to remember which side of the battery is which in the Heat Shrink Sleeve.

Once both wire leads have been inserted and correctly positioned, gently squeeze the two sides of the Coin / Button battery to flatten the spiraling lead wire ends slightly. You do not want to over squeeze since leaving some spring tension is desired to maintain a good mechanical hold between the Coin / Button battery, Wire Leads, and Heat Shrink Sleeve.

Step 6: Applying heat to Shrink Sleeve

Once you are comfortable with the position of the Coin / Button battery and Wire Leads in the Heat Shrink Sleeve, it is time to apply some heat to shrink wrap it. Although the proper way is to use a heat gun to slowly and progressively shrink the Heat Shrink Tubing, an everyday lighter works just as well. If you decide to use a lighter, make sure that the flame does not touch the Wire Lead insulation or the Heat Shrink Tubing skins. Make several evenly paced passes on both sides of the Heat Shrink Sleeve to ensure that you have sufficiently shrunk the sleeve securing the Coin / Button battery and Wire Leads.

After giving it a minute or so to cool, your assembly is complete. At this point, I would recommend testing it with a multimeter to confirm the desired voltage and to ensure no shorts are present.

For added security, a small zip / cable tie can be used to apply additional compression to the heat shrink sleeve, wire leads, and Coin / Button battery package.

--Matt Royer

So frickin easy, but so genius. Thanks for this instructable.

<p>Great instructable!</p>

Great instructable. Definitely just ruined my batteries by leaving the heat gun on it for to long though. Requires a light touch!

Saw feedback for that carbon glue where the writer used it to solder on solar cell tabs. whilst the convenience of connecting to delicate solar cell tabs might make it an attractive proposition, I wonder whether the reduced efficiency due to the extra resistance would mean an alternative might be worth considering. Your instructable is very nicely executed. I pondered the possibility of using silver paint (expensive I know), using hot glue to give mechanical strength. Still, solder does 99% of jobs and your solution to the battery leads on button cells is a pretty clean and elegant way of taking care of those situations where solder isn't viable.

Thinkgeek.com has a wire glue that might be worth looking at as well. I understand your reluctance to exposing the kids to chemicals. Neither Thinkgeek nor the manufacture's web site shows anything other than some guy in ND using it on his kid's science fair project. <br> <br>http://www.thinkgeek.com/product/b70c/?pfm=Search&amp;t=conductive%20glue#tabs

<br>Beyond the potential chemical concerns, the decision not to use Wire Glue (Conductive Glue) for this project was also based on various peer reviews that the Wire Glue had limited tackiness / adhesive qualities on initial application, required components to be held in position or clamped for a long time during drying, and needed to be put on fairly thick to be effective causing concerns around visual appearance. On top of that, I did not think my students had the patients or application precision to effectively use it for this project.<br><br>The same stuff that is sold on ThinkGeek is also sold on Amazon, which has several reviews on the product (both positive and negative). http://www.amazon.com/Electrically-Conductive-Wire-Glue-Bonds/dp/B000Z9H7ZW/ref=cm_cr_pr_product_top<br><br>--Matt Royer

Wow, why didn't I think of that before? <br>Thanks for sharing!

Oh! Yai! Add the small zip / cable tie is the most important and it is very good idea.

How robust is this on the negative wire side. It looks like there may be risk of shorting the battery if the negative lead is pulled too far. <br> <br>I do like your solution though. It's very compact and cost-effective for doing little embedded projects. Thanks for posting.

It is fairly robust from slippage and tolerates general handling well. However, as you advised, proper positioning on the negative terminal is important and you are going to want to avoid &acirc;yanking&acirc; on it. <br> <br>As noted in the instructable, for added security, a small zip / cable tie can be optionally used to apply additional compression to the heat shrink sleeve, wire leads, and Coin / Button battery package if you feel a particular application needs that additional support. <br> <br>--Matt Royer <br>

I see what you did with the first photo of step 1. <br> <br>Personally I've had great success soldering to all sorts of &quot;difficult&quot; surfaces including the inside of a car window demister and battery ends. <br> <br>The three things that make it possible are decent liquid flux, pre-soldered wire, and a really hot iron. I use a butane soldering iron which is perfect. <br> <br>On the other hand I also use and value good heatshrink. But its not cheap, so I've bought some from dx.com which has proved versatile and handy. <br> <br>Good work.

This should work with my light drawing pens although it's a little tricky since I stack the batteries. Thanks

Perhaps some wire glue could help holding the wire in place and conducting well over time (as long as it may last). <br>Nice little project!

The essence of any great Ible is clarity, simplicity and functionality...U got it on all points...A gold star, f'shure...

That sounds all well and good, but is it safe to put heat next to a battery? isn't there potential for defects/explosions?

Most Lithium Coin / Button batteries have a high &ldquo;operating&rdquo; temperature (or maximum sustained temperature during operation) of 60 &deg;C. Polyolefin tubing shrinks quickly at about 90 &deg;C and takes a fraction of a second.<br><br>Short exposure with the minimum required heat to shrink the Polyolefin tubing followed by a ramped cool down is recommended. A sustained high temperature, above operating max thresholds, can cause self-discharging, battery failure, leakage, or catastrophic failure. So, don&rsquo;t leave a sustained heat on it.<br><br>However, with any engineering activity&hellip; I do recommend that you do your own analysis, risks assessment, and draw your own conclusion based on your data.<br><br>--Matt Royer<br>

In any case, i think the heat is far below from what the battery would have suffered if you soldered the leads (as I have done when I needed to put one of these batteries into a GPS to keep memory alive... before heat shrinking). <br> <br>So thank you very much for your idea, another good example of the advantages of KISS (Why solder? Heat shrink is enough!)

That's some good advice. I think I'll try to find my own method for holding a battery. <br> <br>Regardless, I still like your idea of using shrink wrap. Well done.

You can't even draw more than 5mA off these things shorted. so no heating at all

More of an observation of how things have changed in a generation - your instructable is very well thought and laid out, the effort taken is clearly seen. Well done!<br> <br> I have&nbsp;some old&nbsp;books &amp; magazines&nbsp;belonging to my dad that for all intents &amp; purposes were the &quot;Instructables&quot; of the time.<br> <br> The first thing that struck me was the difference in 'instructing' &amp; the projects proposed, you were expected to 'make do', improvise &amp; understand what you were letting yourself in for.&nbsp;<br> <br> The projects proposed were (by today's standards) 'adventurous' - if you could not obtain a specific item&nbsp;...use something close - you were given&nbsp;enough info to get going &amp; expected to continue in your own way - once started if things went wrong well ....you should have known better than to start.&nbsp;<br> <br> In short I could not smile inwardly when reading your instructable &amp; its comprehensive detail -&nbsp;as in the back of my mind I kept on thinking that the 'old instructable' would have began &amp; ended with the original picture ....but in black &amp; white.<br> <br>

Really liked this.

A very clever trick I'll need to remember when I have too many scrap batteries and not enough holders! Thanks!

Great tip, Matt. <br> <br>I like your final photo, which shows an image of the stripped/coiled wire under the heat shrink. <br> <br>Bill W

Good idea. I love heat shrink tubes.

This technique may have just solved my dilemma of how to mount an ultra-bright LED in the nose of a &quot;Subbies&quot; swimming pool toy.